Top level module for Sequel
There are some class methods that are added via metaprogramming, one for each supported adapter. For example:
DB = Sequel.sqlite # Memory database DB = Sequel.sqlite('blog.db') DB = Sequel.postgres('database_name', :user=>'user', :password=>'password', :host=>'host', :port=>5432, :max_connections=>10)
If a block is given to these methods, it is passed the opened Database object, which is closed (disconnected) when the block exits, just like a block passed to connect. For example:
Sequel.sqlite('blog.db'){|db| puts db[:users].count}
Sequel doesn't pay much attention to timezones by default, but you can set it handle timezones if you want. There are three separate timezone settings:
application_timezone - The timezone you want the application to use. This is the timezone that incoming times from the database and typecasting are converted to.
database_timezone - The timezone for storage in the database. This is the timezone to which Sequel will convert timestamps before literalizing them for storage in the database. It is also the timezone that Sequel will assume database timestamp values are already in (if they don’t include an offset).
typecast_timezone - The timezone that incoming data that Sequel needs to typecast is assumed to be already in (if they don’t include an offset).
You can set also set all three timezones to the same value at once via Sequel.default_timezone=.
Sequel.application_timezone = :utc # or :local or nil Sequel.database_timezone = :utc # or :local or nil Sequel.typecast_timezone = :utc # or :local or nil Sequel.default_timezone = :utc # or :local or nil
The only timezone values that are supported by default are :utc (convert to UTC), :local (convert to local time), and nil (don’t convert). If you need to convert to a specific timezone, or need the timezones being used to change based on the environment (e.g. current user), you need to use an extension (and use DateTime as the datetime_class).
You can set the SEQUEL_NO_CORE_EXTENSIONS constant or environment variable to have Sequel not extend the core classes.
For a more expanded introduction, see the README. For a quicker introduction, see the cheat sheet.
The LooserTypecasting extension changes the float and integer typecasting to use the looser .to_f and .to_i instead of the more strict Kernel.Float and Kernel.Integer. To use it, you should extend the database with the Sequel::LooserTypecasting module after loading the extension:
Sequel.extension :looser_typecasting DB.extend(Sequel::LooserTypecasting)
Adds the Sequel::Migration and Sequel::Migrator classes, which allow the user to easily group schema changes and migrate the database to a newer version or revert to a previous version.
The pagination extension adds the Sequel::Dataset#paginate and each_page methods, which return paginated (limited and offset) datasets with some helpful methods that make creating a paginated display easier.
The pretty_table extension adds Sequel::Dataset#print and the Sequel::PrettyTable class for creating nice-looking plain-text tables.
The query extension adds Sequel::Dataset#query which allows a different way to construct queries instead of the usual method chaining.
The schema_dumper extension supports dumping tables and indexes in a Sequel::Migration format, so they can be restored on another database (which can be the same type or a different type than the current database). The main interface is through Sequel::Database#dump_schema_migration.
The sql_expr extension adds the sql_expr method to every object, which returns an object that works nicely with Sequel’s DSL. This is best shown by example:
1.sql_expr < :a # 1 < a false.sql_expr & :a # FALSE AND a true.sql_expr | :a # TRUE OR a ~nil.sql_expr # NOT NULL "a".sql_expr + "b" # 'a' || 'b'
The thread_local_timezones extension allows you to set a per-thread timezone that will override the default global timezone while the thread is executing. The main use case is for web applications that execute each request in its own thread, and want to set the timezones based on the request. The most common example is having the database always store time in UTC, but have the application deal with the timezone of the current user. That can be done with:
Sequel.database_timezone = :utc # In each thread: Sequel.thread_application_timezone = current_user.timezone
This extension is designed to work with the named_timezones extension.
This extension adds the thread_application_timezone=, thread_database_timezone=, and thread_typecast_timezone= methods to the Sequel module. It overrides the application_timezone, database_timezone, and typecast_timezone methods to check the related thread local timezone first, and use it if present. If the related thread local timezone is not present, it falls back to the default global timezone.
There is one special case of note. If you have a default global timezone and you want to have a nil thread local timezone, you have to set the thread local value to :nil instead of nil:
Sequel.application_timezone = :utc Sequel.thread_application_timezone = nil Sequel.application_timezone # => :utc Sequel.thread_application_timezone = :nil Sequel.application_timezone # => nil
Hash of adapters that have been used. The key is the adapter scheme symbol, and the value is the Database subclass.
Array of all databases to which Sequel has connected. If you are developing an application that can connect to an arbitrary number of databases, delete the database objects from this or they will not get garbage collected.
Proc that is instance evaled to create the default inflections for both the model inflector and the inflector extension.
The offset of the current time zone from UTC, as a fraction of a day.
The offset of the current time zone from UTC, in seconds.
Sequel converts two digit years in Dates and DateTimes by default, so 01/02/03 is interpreted at January 2nd, 2003, and 12/13/99 is interpreted as December 13, 1999. You can override this to treat those dates as January 2nd, 0003 and December 13, 0099, respectively, by setting this to false.
Sequel can use either Time or DateTime for times returned from the database. It defaults to Time. To change it to DateTime, set this to DateTime.
Lets you create a Model subclass with its dataset already set. source can be an existing dataset or a symbol (in which case it will create a dataset using the default database with the given symbol as the table name).
The purpose of this method is to set the dataset automatically for a model class, if the table name doesn’t match the implicit name. This is neater than using set_dataset inside the class, doesn’t require a bogus query for the schema, and allows it to work correctly in a system that uses code reloading.
Example:
class Comment < Sequel::Model(:something) table_name # => :something end
# File lib/sequel/model.rb, line 19 def self.Model(source) Model::ANONYMOUS_MODEL_CLASSES[source] ||= if source.is_a?(Database) c = Class.new(Model) c.db = source c else Class.new(Model).set_dataset(source) end end
Returns true if the passed object could be a specifier of conditions, false otherwise. Currently, Sequel considers hashes and arrays of all two pairs as condition specifiers.
# File lib/sequel/core.rb, line 97 def self.condition_specifier?(obj) case obj when Hash true when Array !obj.empty? && obj.all?{|i| (Array === i) && (i.length == 2)} else false end end
Creates a new database object based on the supplied connection string and optional arguments. The specified scheme determines the database class used, and the rest of the string specifies the connection options. For example:
DB = Sequel.connect('sqlite:/') # Memory database DB = Sequel.connect('sqlite://blog.db') # ./blog.db DB = Sequel.connect('sqlite:///blog.db') # /blog.db DB = Sequel.connect('postgres://user:password@host:port/database_name') DB = Sequel.connect('sqlite:///blog.db', :max_connections=>10)
If a block is given, it is passed the opened Database object, which is closed when the block exits. For example:
Sequel.connect('sqlite://blog.db'){|db| puts db[:users].count}
For details, see the “Connecting to a Database” guide. To set up a master/slave or sharded database connection, see the “Master/Slave Databases and Sharding” guide.
# File lib/sequel/core.rb, line 126 def self.connect(*args, &block) Database.connect(*args, &block) end
Convert the exception to the given class. The given class should be Sequel::Error or a subclass. Returns an instance of klass with the message and backtrace of exception.
# File lib/sequel/core.rb, line 133 def self.convert_exception_class(exception, klass) return exception if exception.is_a?(klass) e = klass.new("#{exception.class}: #{exception.message}") e.wrapped_exception = exception e.set_backtrace(exception.backtrace) e end
Load all Sequel extensions given. Only loads extensions included in this release of Sequel, doesn’t load external extensions.
Sequel.extension(:schema_dumper) Sequel.extension(:pagination, :query)
# File lib/sequel/core.rb, line 146 def self.extension(*extensions) extensions.each{|e| tsk_require "sequel/extensions/#{e}"} end
Set the method to call on identifiers going into the database. This affects the literalization of identifiers by calling this method on them before they are input. Sequel upcases identifiers in all SQL strings for most databases, so to turn that off:
Sequel.identifier_input_method = nil
to downcase instead:
Sequel.identifier_input_method = :downcase
Other String instance methods work as well.
# File lib/sequel/core.rb, line 161 def self.identifier_input_method=(value) Database.identifier_input_method = value end
Set the method to call on identifiers coming out of the database. This affects the literalization of identifiers by calling this method on them when they are retrieved from the database. Sequel downcases identifiers retrieved for most databases, so to turn that off:
Sequel.identifier_output_method = nil
to upcase instead:
Sequel.identifier_output_method = :upcase
Other String instance methods work as well.
# File lib/sequel/core.rb, line 177 def self.identifier_output_method=(value) Database.identifier_output_method = value end
Yield the Inflections module if a block is given, and return the Inflections module.
# File lib/sequel/model/inflections.rb, line 4 def self.inflections yield Inflections if block_given? Inflections end
Alias to the standard version of require
The preferred method for writing Sequel migrations, using a DSL:
Sequel.migration do up do create_table(:artists) do primary_key :id String :name end end down do drop_table(:artists) end end
Designed to be used with the Migrator class, part of the migration extension.
# File lib/sequel/extensions/migration.rb, line 124 def self.migration(&block) MigrationDSL.create(&block) end
Require all given files which should be in the same or a subdirectory of this file. If a subdir is given, assume all files are in that subdir.
# File lib/sequel/core.rb, line 191 def self.require(files, subdir=nil) Array(files).each{|f| super("#{File.dirname(__FILE__)}/#{"#{subdir}/" if subdir}#{f}")} end
Set whether to set the single threaded mode for all databases by default. By default, Sequel uses a threadsafe connection pool, which isn’t as fast as the single threaded connection pool. If your program will only have one thread, and speed is a priority, you may want to set this to true:
Sequel.single_threaded = true
# File lib/sequel/core.rb, line 201 def self.single_threaded=(value) Database.single_threaded = value end
Converts the given string into a Date object.
# File lib/sequel/core.rb, line 206 def self.string_to_date(s) begin Date.parse(s, Sequel.convert_two_digit_years) rescue => e raise convert_exception_class(e, InvalidValue) end end
Converts the given string into a Time or DateTime object, depending on the value of Sequel.datetime_class.
# File lib/sequel/core.rb, line 216 def self.string_to_datetime(s) begin if datetime_class == DateTime DateTime.parse(s, convert_two_digit_years) else datetime_class.parse(s) end rescue => e raise convert_exception_class(e, InvalidValue) end end
Converts the given string into a Time object.
# File lib/sequel/core.rb, line 229 def self.string_to_time(s) begin Time.parse(s) rescue => e raise convert_exception_class(e, InvalidValue) end end
Same as Sequel.require, but wrapped in a mutex in order to be thread safe.
# File lib/sequel/core.rb, line 238 def self.ts_require(*args) check_requiring_thread{require(*args)} end
Same as Kernel.require, but wrapped in a mutex in order to be thread safe.
# File lib/sequel/core.rb, line 243 def self.tsk_require(*args) check_requiring_thread{k_require(*args)} end
The version of Sequel you are using, as a string (e.g. “2.11.0”)
# File lib/sequel/version.rb, line 9 def self.version VERSION end
If the supplied block takes a single argument, yield a new SQL::VirtualRow instance to the block argument. Otherwise, evaluate the block in the context of a new SQL::VirtualRow instance.
# File lib/sequel/core.rb, line 251 def self.virtual_row(&block) vr = SQL::VirtualRow.new case block.arity when -1, 0 vr.instance_eval(&block) else block.call(vr) end end
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